The clerk of the board of supervisors of each county shall open and keep a regular set of books, as prescribed by the state auditor, as the head of the state department of audit, or by the director thereof appointed by the state auditor. Such set of books, known as the “uniform system of accounts for the counties,” shall always be subject to inspection within office hours by any citizen desiring to inspect same. Said books shall contain accounts, under headings, corresponding with the several headings of the budget, so that the expenditures under each head may at once be known. It shall be the duty of said clerk to enter all receipts and expenditures in the said books or system of accounts monthly, post and balance the ledgers thereof at the end of each month so that all information needed for a comprehensive review of operations of the county under budgetary limitations may be readily obtainable. Such books shall be paid for out of the general county fund, upon the order of the board of supervisors.